DESCRIPTION (Applicant's Abstract): Pulmonary diseases are a significant factor in morbidity and mortality in the U.S. population. Although there is a strong association between many of these diseases and the use of tobacco products, the influence of toxicants encountered by humans in the environment and in occupational settings is not well established. There are a number of environmental toxicants, which produce highly selective injury to Clara cells of rodent lungs by virtue of their metabolism by the cytochrome P450 monooxygenases. Whether these toxicants are capable of injuring human lunges is not known and cannot be tested directly. One method to establish a better basis for extrapolating from animal models to the human is to understand the underlying mechanisms by which such chemicals produce lung injury. Subsequently, biomarker approaches can be used to indicate whether the biochemical and molecular mechanisms responsible for producing toxicity in the lung exist in humans as they do in the rodent models used to test the chemicals for lung injury. The proposed fellowship work will involve isolation of adducts generated with proteins during metabolism of chemically inert lung toxicants to electrophilic metabolites. Metabolism of these agents in target areas of the lung will be used to generate reactive metabolite-protein adducts. These will be separated by 2D gel electrophoresis, quantified by phosphor imaging, and identified by a combination of MALDI/TOF mass spectrometry and LC/MS/MS. Once target proteins are identified, additional studies will be performed to determine how the biological system metabolizes and eliminates these. The ultimate goal is to develop biomarkers which are related to the formation and covalent binding of reactive metabolites to proteins and which are, in turn, related to the mechanism of cytotoxicity.